Windows 10 install Failure- On Optiplex 7010 SFF

this is the new 2023 Opti Small Form Factor 7010 with Intel 13th gen cpu.

change sata operation to AHCI from RAID in bios, save change, exit.

then proceed w clean install on nvme ssd which is typically the boot drive

When I change the setting from "RAID On" to "AHCI/NVMe" I can install Windows 10 on the 2.5 SSD but  my system will not boot into the original nvme which came with the machine ( it states "INACCESSIBLE BOOT DEVICE"). Must I do a clean install on my nvme or is their a way to get it to boot to the original Windows 11.

If I do a clean install of Windows 11 can I download the original Windows 11 set-up (that will boot in AHCI) from Dell.

There is no need to do a clean install of Windows 11.  You can boot into Safe Mode during BIOS settings change to allow proper AHCI storage driver be installed to your existing Win 11 boot drive.  Follow the steps below to make change:

1. Click the Start Button and type cmd
2. Select the result Run as administrator
3. Type this command and press ENTER: bcdedit /set {current} safeboot minimal
4. Restart the computer and enter BIOS Setup
5. Change setting from RAID ON to AHCI/NVMe
6. Save changes and exit Setup and Windows will automatically boot to Safe Mode.
7. Run elevated cmd command again
8. Type this command and press ENTER: bcdedit /deletevalue {current} safeboot 
9. Reboot the system and Windows will automatically start with AHCI drivers enabled.

I have already changed the BIOS settings to AHCI/NVMe without entering Safe Mode. What part of the procedure should I follow now - to get the Windows 11 NVMe to boot

Thanks so much - worked liked a charm.

You're welcome.

It's also best to only have one boot drive connected when loading OS.

If it's your intent to have both Win11 on the NVMe and Win10  on the SSD to boot from either, I get that too.